arXiv subjects

Milan Wils

Publications and source records attributed to Milan Wils.

5 recordsLinked to original sources

arXiv2026

The impact of physically motivated calibration errors on search pipeline detection parameters for broadband burst Signals

Imperfections in the calibration of gravitational wave observatories introduce frequency dependent amplitude and phase errors on the measured GW signal. Previous unmodelled burst searches have approximated these effects using prescriptions such as a uniform amplitude rescaling or a constant time shift, which do not capture the frequency-dependent structure of calibration errors. This limitation is problematic for core-collapse supernovae, whose predicted GW signals occupy a wide frequency band and exhibit complex time-frequency morphology. In this work, we investigate how realistic calibration errors affect burst search pipelines by combining analytical modelling with large-scale injection campaigns. First-order estimates are derived to quantify how frequency-dependent amplitude and phase errors influence detection statistics such as the coherent network SNR and the correlation coefficient. These calculations predict that the relative impact on the coherent network SNR scales with the signal strength until it reaches an asymptotic value. The effect on the correlation coefficient is most pronounced near the detection threshold and is entirely suppressed at high SNR ratio. Injection studies confirm that calibration errors do modify the detection statistics, but show that the dominant contribution arises indirectly through changes in the number of time-frequency pixels selected in an event. Despite these measurable variations, detection efficiencies as a function of distance differ by less than one percent across all tested waveforms, and explosion-energy limits remain dominated by astrophysical uncertainties rather than calibration uncertainty. These results demonstrate that, at current detector sensitivity, realistic calibration errors have minimal impact on the detectability of broadband GW burst signals. The impact of calibration errors on parameter estimation is left for future work.

gr-qc↗

arXiv2025

Bayesian Calibration of Gravitational-Wave Detectors Using Null Streams Without Waveform Assumptions

We introduce a Bayesian null-stream method to constrain calibration errors in closed-geometry gravitational-wave (GW) detector networks. Unlike prior methods requiring electromagnetic counterparts or waveform models, this method uses sky-independent null streams to calibrate the detectors with any GW signals, independent of general relativity or waveform assumptions. We show a proof-of-concept study to demonstrate the feasibility of the method. We discuss prospects for next-generation detectors like Einstein Telescope, Cosmic Explorer, and LISA, where enhanced calibration accuracy will advance low-frequency GW science.

gr-qc↗

arXiv2024

Null Stream Based Third-generation-ready Glitch Mitigation for Gravitational Wave Measurements

Gravitational Wave (GW) detectors routinely encounter transient noise bursts, known as glitches, which are caused by either instrumental or environmental factors. Due to their high occurrence rate, glitches can overlap with GW signals, as in the notable case of GW170817, the first detection of a binary neutron star merger. Accurate reconstruction and subtraction of these glitches is a challenging problem that must be addressed to ensure that scientific conclusions drawn from the data are reliable. This problem will intensify with third-generation observatories like the Einstein Telescope (ET) due to their higher detection rates of GWs and the longer duration of signals within the sensitivity band of the detectors. Robust glitch mitigation algorithms are, therefore, crucial for maximizing the scientific output of next-generation GW observatories. For the first time, we demonstrate how the null stream inherent in ET's unique triangular configuration can be leveraged by state-of-the-art glitch characterization methodology to essentially undo the effect of glitches for the purpose of estimating the parameters of the source. The null stream based approach enables characterization and subtraction of glitches that occur arbitrarily close to the peak of the signal without any significant effect on the quality of parameter measurements, and achieves an order of magnitude computational speed-up compared to when the null stream is not available. By contrast, without the null stream, significant biases can occur in the glitch reconstruction, which deteriorate the quality of subsequent measurements of the source parameters. This demonstrates a clear edge which the null stream can offer for precision GW science in the ET era.

gr-qc↗

arXiv2024

Potential impact of noise correlation in next-generation gravitational wave detectors

Building upon the statistical formulation for parameter estimation (PE) in the presence of correlated noise proposed by Cireddu et al., we present the initial study to incorporate the effects of correlated noise into the analyses of various detector designs' performance. We consider a two-L-shaped-detector configuration in Europe and compare the expectation of PE of gravitational wave (GW) transients between noncollocated and hypothetical collocated configurations. In our study, we posit the existence of low-frequency correlated noise within the 5-10 Hz range for the collocated detector configuration, with a varying correlation. In this specific detector setup, our observations indicate an enhancement in the precision of intrinsic parameter measurements as the correlation increases. This trend suggests that noise correlation may beneficially influence the accuracy of PE. In particular, when the noise is highly correlated, the uncertainty on chirp mass decreases by up to $30\%$. The absence of an inter-European baseline does hinder the estimation of the extrinsic parameters. However, given a realistic global network with the additional detector in the US, the uncertainty of extrinsic parameters is significantly reduced. This reduction is further amplified as the noise correlation increases. When the noise correlation exceeds a certain level, the collocated configuration outperforms the noncollocated configuration. For instance, when the correlation is high, the collocated configuration decreases the $90\%$ credible area of sky location by up to $10\%$ compared to the noncollocated configuration. We conclude that the impact of noise correlation is not trivial and can potentially alter both the quantitative and qualitative outcomes in detector performance. We therefore recommend the inclusion of noise correlation for a comprehensive assessment of the design of third-generation GW detectors.

gr-qc↗

arXiv2023

Likelihood for a Network of Gravitational-Wave Detectors with Correlated Noise

The Einstein Telescope faces a critical data analysis challenge with correlated noise, often overlooked in current parameter estimation analyses. We address this issue by presenting the statistical formulation of the likelihood that includes correlated noise for the Einstein Telescope or any detector network. By considering varying degrees of correlation, we probe the impact of noise correlations on the parameter estimation analysis of a GW150914-like event. We show that neglecting these correlations may significantly reduce the accuracy of the chirp mass reconstruction. This emphasizes how critical a proper treatment of correlated noise is, as presented in this work, to unlocking the wealth of results promised by the Einstein Telescope.

gr-qc↗